What actually causes acne?

Excess sebum, blocked follicles from abnormal keratin shedding, *Cutibacterium acnes* bacteria, and inflammation — driven by hormones and genetics. Diet plays a modest role (high glycaemic load and possibly skim milk). It is not caused by poor hygiene, and over-washing worsens it.

Jawline and lower-face acne in adult women often has a hormonal pattern and may respond to hormonal treatment or spironolactone alongside topicals.

Painful deep nodules should be treated early by a dermatologist — scarring from untreated nodular acne is far harder to fix than the acne itself.